Patent GB-981020-A (GB)
Title: Improvements in or relating to a process for manufacturing synthetic resin sheets and product obtained by this process
IPC: F23C15/00
Filed: 1961-02-23
Abstract: Reinforced synthetic resin sheets capable of being shaped mechanically may be made by (a) causing a permeable supporting layer formed from a reinforcing material to be impregnated and, if desired, coated with a gel formed by the partial polymerization of an unsaturated polyester resin composition, said partial polymerization being initiated by the action of a metallic reducing salt and the extent of said partial polymerization being controlled by the action of a modifying agent comprising any one of, or a mixture of two or more of, tetrahydrofuran, furfurol, dioxan and dimethylformamide, said unsaturated polyester resin composition containing a polymerization catalyst whereby on the application of heat and/or an accelerator to said composition the polymerization thereof may be completed and (b) thereafter subjecting one or both faces of the permeable supporting layer, which is impregnated and optionally coated with the partially polymerized unsaturated polyester resin composition, to the action of heat and/or a polymerization accelerator so as to form a thin more fully polymerized surface layer upon one or both faces thereof.  The preferred metallic reducing salt is stannous chloride and in one embodiment the metallic reducing salt and modifying agent may be mixed with ethylene glycol or a derivative thereof.  In step (a) above, the permeable supporting layer is first impregnated with a solution and/or dispersion of the metallic reducing salt in the modifying agent, dried and then impregnated with the unsaturated polyester resin composition. Alternatively, some or all of the solution and/or dispersion of the metallic reducing salt in the modifying agent can be incorporated in the unsaturated polyester resin composition before the latter is applied to the supporting layer.  In step (b) the further polymerization may be carried out using dimethylaniline or a mixture of dimethylaniline, N, N1-diphenylguanidine and a modifying agent, e.g. toluene diisocyanate. Alternatively, alkyl mercaptans, e.g. lauryl mercaptan, may be used alone or in combination with dimethylaniline. Specifications 938,403 and 941,481 are referred to.ALSO:Reinforced synthetic resin sheets capable of being shaped mechanically may be made by (a) causing a permeable supporting layer which is a sheet of fabric or fibre, e.g. paper, or other suitable natural or synthetic material, to be impregnated and, if desired, coated with a gel formed by the partial polymerization of an unsaturated polyester resin composition, said partial polymerization being initiated by the action of a metallic reducing salt and the extent of said partial polymerization being controlled by the action of a modifying agent comprising any one of, or a mixture of two or more of, tetrahydrofuran, furfurol, dioxan and dimethyl-formamide, said unsaturated polyester resin composition containing a polymerization catalyst whereby on the application of heat and/or an accelerator to said composition the polymerization thereof may be completed, and (b) thereafter subjecting one or both faces of the impregnated and optionally coated sheet of fabric or fibre to the action of heat and/or a polymerization accelerator so as to form a thin more fully polymerized surface layer upon one or both faces thereof.  In step (a) above the sheet of fabric or fibre is first impregnated with a solution and/or dispersion of the metallic reducing salt in the modifying agent, dried and then impregnated with the unsaturated polyester resin composition.  Alternatively some or all of the solution and/or dispersion of the metallic reducing salt in the modifying agent can be incorporated in the unsaturated polyester resin composition before the latter is applied to the sheet of fabric or fibre.  In step (b) the further polymerization may be carried out using dimethylaniline or a mixture thereof with N,N1-diphenylguanidine and a modifying agent, e.g. toluene diisocyanate.  Alternatively alkyl mercaptans may be used alone or in combination with dimethylaniline.  Specifications 938,403 and 941,481 are referred to.ALSO:Reinforced synthetic resin sheets capable of being shaped mechanically may be made by causing a permeable supporting layer formed from a sheet of fabric, fibre or paper to be impregnated and, if desired, coated with a gel formed by the partial polymerization of an unsaturated polyester resin composition, said partial polymerization being initiated by the action of a metallic reducing salt and the extent of said partial polymerization being controlled by the action of a modifying agent comprising any one of, or a mixture of two or more of, tetrahydrofuran, furfurol, dioxan and dimethylformanide, said unsaturated polyester resin composition containing a polymerization catalyst whereby on the application of heat and/or an accelerator to said composition the polymerization thereof may be completed and (b) thereafter subjecting one or both faces of the impregnated and optionally coated sheet of fabric, fibre or paper to the action of heat and/or a polymerization accelerator so as to form a thin more fully polymerized surface layer upon one or both faces thereof. In step (a) above, the sheet of fabric, fibre or paper is first impregnated with a solution and/or dispersion of the metallic reducing salt is the modifying agent, dried and then impregnated with the unsaturated polyester resin composition. Alternatively some or all of the solution and/or dispersion of the metallic reducing salt in the modifying agent can be incorporated is the unsaturated polyester resin composition before the latter is applied to the sheet of fabric, fibre or paper.  In step (b) the further polymerization may be carried out using dimethylaniline or a mixture thereof with N, N1-diphenylguanidine and a modifying agent e.g. toluene diisocyanate.  Alternatively alkyl mercaptans may be used alone or in combination with dimethyl aniline.  Specifications 938,403 and 941,481 are referred to.